1. Field of the Invention
The present invention concerns an electrostatic coating apparatus used for coating an electroconductive paint such as an aqueous paint, a slurry paint or a metallic paint by using an electrostatic coating apparatus applied with a high voltage.
2. Description of the Prior Art
When an electroconductive paint such as an aqueous paint is used in an electrostatic coating machine applied with a high voltage, it is necessary to electrically insulate paint supply systems from the electrostatic coating machine for preventing current leakage caused by the high voltage. Accordingly, in a multi-color electrostatic coating apparatus used for coating car bodies under color-change of paints of so many different colors, which may include several tens of tones, insulation means have to be applied to all of paint supply pipelines or paint reservoirs on every color of paint, which has been troublesome and expensive.
In view of the above, in the electrostatic coating for car bodies, manufactures such as automobile manufacturers hesitate to use aqueous paints at present, although aqueous paints may be preferable for use, because they cause less pollution of air, because they contain less volatile organic compounds than do organic solvent-based coating compositions. Instead, electrically insulative resin paints that require a great amount of deleterious organic solvents continue to be used predominantly.
However, social movements for environmental protection have been raised world-world in recent years and it has been advocated to more stringently regulate and thereby restrict the use of organic solvents that release environmental pollutants such as hydrocarbons also in the field of coating industry.